The access driver runs inside the database server. This is different from SQL*Loader, which is a client program that sends the data to be loaded over to the server. This difference has the following implications:
The server must have access to any files to be loaded by the access driver.
The server must create and write the output files created by the access driver: the log file, bad file, discard file, and also any dump files created by the
ORACLE_DATAPUMP access driver.
The access driver requires that a directory object be used to specify the location from which to read and write files. A directory object maps a name to a directory name on the file system. For example, the following statement creates a directory object named
ext_tab_dir that is mapped to a directory located at
CREATE DIRECTORY ext_tab_dir AS '/usr/apps/datafiles';
Directory objects can be created by DBAs or by any user with the
To use external tables in an Oracle Real Applications Cluster (Oracle RAC) configuration, you must ensure that the directory object path is on a cluster-wide file system.
After a directory is created, the user creating the directory object needs to grant
WRITE privileges on the directory to other users. These privileges must be explicitly granted, rather than assigned through the use of roles. For example, to allow the server to read files on behalf of user
scott in the directory named by
ext_tab_dir, the user who created the directory object must execute the following command:
GRANT READ ON DIRECTORY ext_tab_dir TO scott;
SYS user is the only user that can own directory objects, but the
SYS user can grant other users the privilege to create directory objects. Note that
WRITE permission to a directory object means only that the Oracle database will read or write that file on your behalf. You are not given direct access to those files outside of the Oracle database unless you have the appropriate operating system privileges. Similarly, the Oracle database requires permission from the operating system to read and write files in the directories.